In the production of cellulose ply material, for example rolls of toilet paper, rolls of kitchen towels, paper handkerchiefs, paper napkins and the like, a cellulose ply is usually embossed, by passing it through an embossing nip formed by a pair of steel rollers or by a pair constituted by a roller made of steel or other relatively rigid material and a roller coated with a yielding material like rubber. The steel roller has protuberances entering the elastically yielding coating of the pressure roller. The pressure between the embossing roller and the pressure roller causes the permanent deformation of the web of cellulose material which passes through the embossing nip between the embossing roller and the pressure roller. Two or more plies, at least one of which, or some of which, or all are embossed, are then bonded together in order to for a multi-ply web material. The web material may be wound in order to form rolls, or it may be cut and folded to form napkins, handkerchiefs and the like.
Each ply can in turn be composed of one or more layers of cellulose material.
The embossing pattern has both decorative and functional purposes. From a functional viewpoint, the embossing creates limited areas, onto which glue is applied for bonding together multiple plies forming the web material. A further purpose of embossing is to increase the overall thickness of the web material, to increase the softness and the absorption capacity thereof, as well as to increase other functions thereof known to those skilled in the art.
Generally speaking, an embossing device is a device performing an embossing processing on at least one ply and, in case, bonding two or more plies together by means of lamination, for example using glue applied on at least one of the plies, preferably on the top surfaces of at least some embossing protuberances formed on one or more plies.
In order to satisfy the needs of the modern tissue paper processing lines, it is necessary to replace the embossing rollers of the embossing device, with the purpose of both changing the pattern of the web material, and modifying the technical and functional features thereof, for example to switch from manufacturing of toilet paper to manufacturing of kitchen towels and vice versa. In fact, since embossing has not only aesthetical purposes but also, in some cases, functional purposes, embossing patterns suitable for manufacturing of toilet paper are not always suitable for manufacturing kitchen towels, and vice versa. Also consistency, grammage and content of the cellulose plies may differ depending on the type of articles to be produced, and different embossing patterns may be required for different products.
Embossing units or devices have been studied, having particular solutions for making the roller replacement simpler and quicker.
WO-A-2015/150452 discloses examples of embossing or embossing-laminating devices, provided with a magazine for interchangeable embossing rollers. In this way, it is possible to replace the embossing roller(s) mounted in the embossing device with other embossing rollers stored in the magazine. A specific handling member is provided to this end, transferring embossing rollers from the magazine to the supports for the embossing rollers, with which the embossing device is equipped, and vice versa. In some embodiments disclosed in WO-A-2015/150452 a magazine for embossing rollers is provided, comprising a carriage provided with a plurality of embossing roller support seats adjacent to one another according to an alignment direction, and a guide system for guiding the carriage in a handling direction parallel to the alignment direction of the support seats.
This magazine is particularly useful for making the embossing device more efficient and versatile, allowing the embossing rollers to be replaced quickly.
However, there is still a need for further improvements of embossing roller magazines, and embossing devices comprising said magazines, in order to make the replacement of the embossing rollers easier, more effective and quicker, further increasing the performance of the embossing device.